1. Field of the Invention
The present invention relates to the field of micro-array assay technology. More particularly, the present invention relates to methods for the preparation of substrate coated micro-array supports. Even more particularly, the present invention relates to the use of centripetal force to prepare coated micro-array support surfaces evenly coated with substrate.
Micro-array platforms are devices that comprise support material that is coated with a substrate to localize an assay reaction. A variety of support and coating materials have been used and are selected based on the nature of the assay for which the micro-array will be used. In the case of micro-arrays in which the substrate material is coated onto the surface of a support material, the substrate may be applied by dipping the support material into liquid or semi-solid substrate or dripping the substrate onto the surface of the support. Spin coating is one method for spreading the substrate across the surface of a support that consists of applying centripetal acceleration to the support material after a substrate has been applied.
2. State of the Art
Prior art spin coating techniques whereby a single side of a support is coated with a substrate require a multiplicity of handling steps in the mounting of the support, the coating of the substrate, the semi-curing or drying of the surface, removal of excess substrate and remounting and repeating of the coating cycle. Importantly, there are practical limits to the evenness of a coating and thinness of the coating obtainable by spin coating methods. U.S. Pat. No. 3,730,760 describes a method in which centrifugal forces are applied to coated substrate supports. This method creates a ramp effect, whereby the inner diameter edges of the coated substrate are thinner in thickness than the outer diameter edges of the coated substrate. Control of this ramp effect is difficult but desirable as it affects the relative unit volume density distribution of suspended particulates in the coating substrate film.
A film formation method involving spin coating comprises adding a coating substrate solution drop-wise to a support to be coated and drawing the coating solution thereon by centrifugal force, so as to form a thin film on the support. This method causes film thickness distribution to occur. Japanese Patent 2,942,213, discloses a modification to this method wherein the drop wise coating solution is added to a sealed cup. Japanese Patent 3,231,970 discloses a modification to the sealed cup method in which gas is injected into the cup.
U.S. patent application 2006073521 discloses a spin coating method wherein the support is rotated in a state where the surface of the support to be coated is inclined during coating. The objective of this method is to produce a substrate film on the surface of the support with a film thickness that is even across the surface of the support. Each of these prior art references describe methods in which a single coating step is used in the preparation of a support having a film or coating of substrate evenly distributed across its surface. However, none of these methods adequately prevent unevenness and ramp effects in the film thickness generated in the substrate and manifested at marginal parts of the support.